joel,
To a certain extent the answer would depend on the bullet. Some of the Ballistic Tips are tougher than others, and so are some of the AccuBonds. Any of the "hunting" Ballistic Tips will kill elk neatly if put in the ribs, but the The 120 and 150 7mms, 180 .30's and 200 .338 Ballistic Tips are all a little stouter than average. Same deal with AccuBonds. The lighter, smaller-diameter models are designed more for deer than bigger game, while the larger ones will retain more weight. That said, the smallest AB I've used on elk-sized game is the 140-grain .270, and it worked fine.
In general I have grown very fond of bonded bullets for game larger than deer over the past few years, since they seem to kill quicker than monolithic bullets, either due to losing some weight or opening wider.
But I still use plenty of Partitions too; this year I took 13 big game animals (about average for me) and used Partitions on six of them, though four of the six were from one rifle (9.3x62) on a hunt in Africa. That's actually a higher percentage of Partitions than in most years anymore; I try to use a wide variety of bullets to see how they act on game.
I realize this is all kind of confusing, but there really is a lot of overlap in the performance of various types of bullets. There is no set performance level from any certain type of bullet. For instance, even Sierra GameKings vary quite a bit in the way they act on game, depending on weight, caliber and cartridge. The bigger GK's are designed considerably tougher than the lighter ones, as with many other bullets.
